1. Field of Use
This invention relates generally to data processing systems. More specifically, it relates to controllers for controlling data transfers between a data processing system and peripheral devices.
2. Prior Art
Most modern data processing systems rely on a controller for controlling data transfers between the central processing unit (CPU) on a system bus and the peripheral devices. With the advent of more and more types of peripheral devices having vastly different operating characteristics, there has been an increased demand for controllers capable of controlling data transfers for the entire range of devices having differing operating characteristics. Moreover, there has also been a greater demand for controllers to simultaneously service a larger number of devices. In order to fulfill these increased demands, manufacturers have begun to use microprocessors in controllers.
The addition of microprocessors to controllers has also mandated the addition of a control store for storing the microinstructions that the microprocessors execute.